docs: def future_exceptions(context, rrevent=None):
      """
      Displays a list of all the future exceptions (extra info, cancellations and
      postponements) for a recurring event.  If the recurring event is not
      specified it is assumed to be the current page.
      """
      request = context['request']
      if rrevent is None:
          rrevent = context.get('page')
      if rrevent:
          exceptions = rrevent._futureExceptions(request)
      else:
          exceptions = []
      return {'request':    request,
              'exceptions': exceptions}